[ARC5] BC-458-A Questions and an ARC-2 question
David Stinson
arc5 at ix.netcom.com
Mon Dec 30 14:41:50 EST 2024
Hello, Rob. Sorry it takes me so long these days.
Life interferes.
Sometimes in Command Set Transmitters,
it will seem impossible to align the
central PA padding variable or one of
the ganged variables.
When working on our sets. I'm finding
oxidation and corrosion of grounds and
unsoldered connections, like press-fit parts
held together by friction, to be nearly as big
a problem as bad caps. The last ART-13 I
revived, I could place an Ohmmeter probe
on a ground on the left of the chassis and
one on the right, and read 3300 ohms.
Have seen normal-looking grounding screws
show completely open to the chassis.
A quarter-turn left and right usually fixes those,
but some things need extra effort.
In the earlier-production ATA/SCR-274N/AN-ARC-5
transmitters (and some later non-A.R.C. sets), the
stators of the big variable capacitors are made of
stacked parts which are held-together by a metallic
strip. The strip is placed across the assembly with
posts through the strip, which are then "upset"
in a press.
Here are photos of the "connection strip":
https://photos.app.goo.gl/xuZceJycJxJw7dVT8
https://photos.app.goo.gl/fcpJDs2z3LQsUw7BA
Next are a couple of views of the crud and
corruption which can bedevil these assemblies.
https://photos.app.goo.gl/GZPXrjGW2Htuqmnb6
https://photos.app.goo.gl/UKf9j7YwafFLq3Pw9
With the end-on view, you can see how badly
these can deteriorate, but I have seen pretty, NOS
looking strips with no continuity at all.
The end-view photo, the connection on the right
was partially cleaned with a file, some
non-acid flux applied and heated with a 100W iron.
One must be careful and observant, since there
is a plastic ball holding the strip and stator in place.
This problem appeared during the war, because
I have a NOS in original box oscillator capacitor
and it has been soldered.
https://photos.app.goo.gl/YSWoM2BcKB8QcwHt7
I hope this is helpful.
Lord Bless us for the year ahead.
73 DE Dave AB5S
On 12/27/2024 1:10 PM, Robert Steenburgh wrote:
> Hi Dave:
> Were you ever able to dig out a capacitor to describe where the
> press-fit strip that needs soldering is? I think I'm beginning to run
> into a similar problem with the T-22/ARC-5 I picked up earlier this year.
>
> I've got a 40W Weller pencil iron (hefty tip) and a Hakko (smaller
> tip). If I need to pick up a soldering gun to do the job, I can get one.
>
> Hope your holiday has been good so far.
>
> Cheers,
> Rob
>
>
> On Tue, Aug 6, 2024 at 4:26 AM David Stinson <arc5 at ix.netcom.com> wrote:
>
> Morning, Robert.
> Haven't forgotten you. Got to dig-out a cap
> so I can take a photo and work keeps interfering.
> Will get it done. Thanks for your patience.
>
>
> On 8/5/2024 2:09 PM, Robert Steenburgh wrote:
>> Hi Dave -
>>
>> Thank you for your response. I appreciate the insight on the
>> ARC-2. That may be a rig that's too complex for my skill set and
>> available time.
>>
>> I think I figured out where the press-fit joint is after
>> re-reading your description and referring to the underside of my
>> rig. In the second picture in my earlier email, it appears to be
>> the point on the lower right of the variable capacitor, where the
>> wire feeds through. I've got a variable temp Hakko soldering
>> iron, but I'm not sure if it'll cut it.
>>
>> 73,
>> Rob
>>
>>
>>
>> On Sun, Aug 4, 2024 at 8:10 PM David Stinson <arc5 at ix.netcom.com>
>> wrote:
>>
>> Hello, Rob
>> I've been out-of-town all weekend and just got in.
>> I will get with you when I get home from work tomorrow.
>>
>> On the ARC-2: Is is a heavy handful, but a neat machine.
>> You must be tolerant of selectivity which makes an ARC-5 40
>> meter receiver look like a Q-Multiplier. It's BROAD,
>> accessories are hard to find and it's not easy to
>> troubleshoot. If you get one that's working and lube
>> everything properly (plus change the BFO injection cap.
>> Details later.) it can be an interesting and cool rig. Will
>> get with you after work.
>> GL OM ES 73 DE Dave AB5S
>>
>> On 8/3/2024 7:59 PM, Robert Steenburgh wrote:
>>> Dear Dave:
>>>
>>> I was reading an article you wrote about "Getting Your
>>> "ARC-5" Transmitting Without Hacking It Up.
>>> In the article, you noted:
>>>
>>> image.png
>>> Below is a picture of my BC-458-A in its original condition
>>> before I put it on the air.
>>>
>>> 4610180473_0ec0cd036e_b.jpg
>>> Here's a close-up of the capacitor in the rear:
>>> PXL_20230515_175309951.jpg
>>> Where should I look for the press-fit metal strip and the
>>> stator connection?
>>>
>>> My transmitter has begun exhibiting the symptoms you
>>> describe - sudden intermittent detuning and power loss. It
>>> generally puts out a reliable 30W, but sometimes suddenly
>>> drops to <=15W. So, I'd like to try heating/soldering it as
>>> you describe. Was the soldering gun you used one of those
>>> pistol grip Weller types with a trigger?
>>>
>>> Finally, on your QRZ page, I saw your RT-91/ARC-2
>>> transceiver. I just saw one of those up-close today at a
>>> gentleman's house I visited to buy a couple of ARC-5s (40m
>>> and 80m). Has yours proven relatively reliable? The
>>> mechanical aspects of it (e.g. motorized) made me wonder how
>>> robust they were and whether owning one was a blessing or a
>>> curse.
>>>
>>> The only rig I've ever used during wartime was the
>>> Transworld-Datron TW100F
>>> <http://www.radiomilitari.com/tw100f.html> fly away
>>> transceiver. My role in the Air Force was to use it to
>>> transmit and receive weather observations during the Gulf
>>> War. I haven't run across them much in the surplus world.
>>>
>>> Best Regards,
>>> Rob
>>>
>>>
>>
>
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